1. Field of the Invention
The present invention relates in general to a spacing member and, more particularly, to a spacing member for use in an electrochromic device, (e.g. window, mirror, transparency, etcetera) which facilitates substantially uniform spacing between the substrates of an electrochromic device. A spacing member of the present invention also enhances manufacturing of an electrochromic device by dissolving, at a controlled rate, in the solvent of the electrochromic medium within the electrochromic device.
2. Background Art
Electrochromic devices have been known in the art for several years. Furthermore, the utilization of spacing members (i.e. spacer beads) generally within the seal region of an electrochromic device is likewise well known. See, for example, U.S. Pat. No. 5,790,298 entitled “Method Of Forming Optically Transparent Seal And Seal Formed By Said Method,” U.S. Pat. No. 6,157,480 entitled “Seal For Electrochromic Devices,” and U.S. Pat. No. 6,195,193, entitled “Seal For Electrochromic Devices,” all of which are hereby incorporated herein by reference in their entirety.
While the above-identified references disclose utilizing a plurality of generally non-dissolving spacing members, including glass, plastic, and clay beads or rods, which are generally incorporated into the seal region of an electrochromic device, to the best of Applicant's knowledge, utilizing such spacing members in the in-view region of an electrochromic device can, indeed, be problematic. Such problems include visual irregularities due to, among other things, generally undissolved (i.e. partially dissolved) spacing members which affect coloring and/or clearing of electrochromic devices—just to name a few.
In an attempt to generate uniform cell spacing between substrates in the in-view region of electrochromic devices, spacing members fabricated from polymethylmethacrylate (PMMA) have been utilized. See, for example, U.S. Pat. No. 5,940,201 entitled “Electrochromic Mirror With Two Thin Glass Elements And A Gelled Electrochromic Medium,” which is hereby incorporated herein by reference in its entirety. While PMMA based spacing members can be dissolved in certain solvents and, in turn, reduce or eliminate any visual irregularity concerns, PMMA spacing members are highly problematic because it can take several hours to fully dissolve such spacing members in current electrochromic systems—which substantially increases manufacturing time and cost.
In addition, utilizing PMMA based spacing members can be especially problematic if a cross-linked polymer matrix is associated with the electrochromic medium. Specifically, if the cross-linked polymer matrix forms before the PMMA spacing members completely dissolve, it can be extremely difficult, even at elevated temperatures, to avoid visual irregularities associated with even small quantities of undissolved and/or partially dissolved PMMA spacing members.
It is therefore an object of the present invention to provide a spacing member that remedies the aforementioned difficulties and/or complications associated with the utilization of conventional spacing members in electrochromic devices.
These and other objectives of the present invention will become apparent in light of the present specification, claims, and drawings.